Boundary of Flames
by Crossgap
Summary: An unknown force from outside in the presence of flames threatens to destroy the Hakurei Border and consume Gensokyo. Yukari decides to investigate as the Shrine Maiden and the inhabitants travel beyond the border to prevent such a fate from happening. They will receive help from an unlikely outsider: The Flame-Haired, Burning-Eyed Hunter.
1. Prologue

**Boundary of Flames**

(a Touhou Project & Shakugan no Shana crossover)

**Author's Note: "After my recent failure to cross Touhou with Tales of the Abyss (Danmaku shooters don't mix well with linier-motion RPGs), I have played Touhou up to Ten Desires to finally get to know the characters and Gensokyo a lot more than before. So I have decided to cross Touhou with Shakugan no Shana; a well-known but not-often-liked anime and one of my personal favorites. I have a feeling that this story will have potential but that is up to you to decide."**

"**For those of you who don't know what Touhou is, Touhou is a Danmaku (Bullet Hell) shooting game and one of the most popular but VERY HARD games created to date. Look it up online for more information because I don't want to spoil anything at this point."**

"**Without further ado, I give you the story. Enjoy! ^^"**

**DISCLAIMER: Touhou Project belongs to ZUN and Team Shanghai Alice. Shakugan no Shana belongs to Yashichiro Takahashi, Noizi Ito, and ASCII Media Works. I do not own anything from both series.**

* * *

**Prologue**

Gensokyo; a land of magic and mysteries that has kept itself isolated from the rest of the world by a supernatural border known by the residents as the Hakurei Border. Inside Gensokyo are a variety of mythical creatures you would expect to see in a fairy tale or traditional folklore. They live inside Gensokyo to hide their very existence from the outside world and the very humans that would disturb their peace. Humans live inside Gensokyo as well but don't actually co-exist with these creatures (although Byakuren would wish for that to happen) for obvious reasons. These creatures called Youkai see humans as weak and inferior beings and often hunt them for food. Because of this, humans are prompted to hunt down youkai to preserve their own existence. The unsteady peace between the two has led to many conflicts and incidents in Gensokyo, as far as the Youkai of Boundaries; Yukari could remember.

However, unknown to both humans and youkai, they didn't expect a new incident to emerge from outside the border.

"CRACK!"

On the path leading to the Myouren Temple, the dowser mouse youkai Nazrin was to first to notice a small crack in the sky. What she also noticed is that there's something seething out of the crack and it appeared to be azure-colored flames. Nazrin was surprised by this, as it is something that she has never seen before. "What is that? Is it normal for the sky to crack like that?" she wondered as she continued to float to the temple.

Nazrin was not the only youkai to notice the abnormality in the sky. In the Netherworld, Youmu Konpaku can see the crack as plain as day due to the Netherworld being close to it. She also noticed the flames seething out of it and felt a strange spiritual energy emanating from the flames. "This energy, it is not friendly to the living and the dead. I have a bad feeling about this." she said to herself.

At the far reaches of Gensokyo in an unknown house, no one could sense the abnormality better than Yukari herself. Being the Youkai of Boundaries, she could sense the strange energy rippling across the entire Hakurei Border. Yukari was uneasy. Despite being experienced with the outside world, she had never seen or sensed these flames before in her life. "This shouldn't be right." She said to herself. "The outside world shouldn't have anything supernatural that could be harmful to the border. I better go investigate."

That being said, Yukari goes back inside her house to confront her two shikigami; the nine-tailed kitsune Ran Yakumo and the two-tailed nekomata Chen. Ran can see Yukari's expression and can tell that she is worried about something.

"Is something wrong Yukari-sama?" Ran asked. With a more serious tone than her usual, Yukari answered. "Ran, it's time to go investigate the outside world."

"But why is that Yukari-sama?" Ran asked.

"There is something that concerns me with the Hakurei Border. A strange supernatural energy is seeping through the border from the outside world into Gensokyo that could threaten to destroy the border itself and expose our existence." Yukari answered.

"A supernatural energy? But shouldn't the outside world contain no trace of spiritual magic left?" Ran wondered.

"That's what I like to investigate about. Follow me Ran." Yukari said.

"Hai Yukari-sama!" Ran said. As the two are prepared to leave, Chen approached Ran. "Should I come as well Ran-sama?" she asked.

"Chen, you stay here and keep an eye on the border abnormality." Yukari answered. "If it gets worse, head to the Hakurei Shrine to notify the shrine maiden."

"Hai Yukari-sama!" Chen answered. Yukari and Ran then leave the house and started flying to the crack in the sky close to the Netherworld. As they approached the crack, both Ran and Yukari started to sense just how powerful these flames were. It was something they could not grasp in their minds.

"These are not ordinary flames." Yukari said as she closely examined them. "They have enough power to eat through existence and are consuming the border as we speak. Not even Mokou's flames can do this much damage."

"Be careful Yukari-sama! We do not know what these flames could do to a youkai." Ran said concerned.

"You can relax Ran. You know very well that my years of wisdom and experience have taught me to proceed with caution when dealing with an unknown presence. These flames are not the main cause of the abnormality however. They're just making it worse."

"Shall we proceed into the outside world as planned Yukari-sama?"

"Yes. Let's find the true cause of the abnormality." Yukari answered as she smirked a bit.

Yukari then opened a strange portal with red ribbons on either side of its edges. Inside the portal were strange creepy eyes that seem to do nothing but stare out into space. These were Yukari's famous gaps she uses to travel around Gensokyo, even outside the border. With the gap opened, both Yukari and Ran stepped into the gap and it closes. Another gap opens outside of the Hakurei Border and Ran and Yukari step out. What they find was beyond what they can comprehend of the outside world. Everything was covered in a dark-red haze. It was not like the Scarlet mist that Remilia spread throughout Gensokyo, this red haze was even more darker and it appears to have time-stopping capabilities as Yukari and Ran observed that the animals were colorless and completely frozen.

"This… This can't be the outside world I know. What type of realm have we stepped into?" Yukari wondered.

"It looks like we may need Sakuya's help to deal with the situation. Time here is completely static." Ran said.

"Yes, so it seems. It is possible that there may be some youkai in the outside world with the ability to…" Before Yukari could finish, she noticed a barrage a fireballs heading towards Ran and herself.

"Ran, graze!" Yukari shouted. Ran took notice and the two youkai grazed the fireballs as if they were ordinary bullets. However, after grazing, they saw the fireballs impact the Hakurei Border at various spots.

"I see. So these are the flames that were seeping through the border. They don't appear as strong as I thought they would to pierce through so what is the main cause of the abnormality?" Yukari wondered.

Just then, Yukari and Ran hear a crack. As they looked at the border, they notice the crack present was starting to increase in size. The red haze appears to be digging through the border without difficulty. "Perhaps the red haze around us is playing a role in weakening the border." Yukari said.

Ran then looked in the direction where the fireballs came from to notice a battle between two figures. "Yukari-sama! Down there!" She pointed. Yukari saw the figures battling it out with each other with supernatural abilities; something that she thought was never possible outside Gensokyo. She looked closer to see the two figures. One appeared to be a young girl with blazing-red hair and holding a sword, the other was an anonymous figure attacking with a relentless barrage of fireballs. Both Yukari and Ran watched the battle from the air above.

"Are these two youkai? They don't appear to be human." Ran said.

"I'm not the one to judge like Shikieiki but judging by the surroundings and their abilities, they may be youkai." Yukari answered.

"Then it's possible that they may be the cause of the abnormality of the border." Ran said.

"We'll see what happens first. I don't want any unnecessary involvement with outsiders." Yukari assured Ran.

As the two youkai watched the battle, it wasn't long before the blazing-haired girl slain her opponent with her sword. As she sheathed it back into what appears to be a cape, she lifted her finger and activated some sort of spell. First, there was a wave of distortion, then the red haze around her disappeared and time had resumed back to its original pace. Everything was completely back to normal to both Yukari's and Ran's surprise. However, when the red haze was lifted, the distortion of time resuming caused the crack in the Hakurei Border to expand.

"I see. So the main cause of the abnormality was the result of the red haze that stopped time. Such a powerful youkai like her could pose a threat to Gensokyo." Yukari said.

"Should we engage the youkai Yukari-sama?" Ran asked.

"No. Instead, I have a plan." Yukari said as she smirked. "In the meantime, return to Gensokyo and gather whoever can deal best for this situation."

"Understood!" Ran nodded. Yukari then created a gap for Ran to return. As Ran disappeared in the gap, Yukari turned her attention to the girl with a smirk before disappearing in her own gap.

* * *

Back on the ground, the girl looked around her surroundings to make sure there weren't any more opponents. "There doesn't appear to be more tomogara in this area." She said to no one in particular. "Let's head back to Misaki City."

"_Yes. We can't forget about the Reiji Maigo. It will only be a matter of time before Bal Masque makes another move._" A voice said from nowhere. The girl nodded to the mysterious voice with a smile. "Yuji… I'm coming home."

As the girl sprouted what appeared to be wings made of flames and flew off in the distance, Yukari opened a gap to where she once stood. "Misaki City now is it? I guess it has been a while since I had to do anything outside of Gensokyo. Time to find out more about this youkai." She said. Yukari then disappeared in the gap again.

**End of Prologue**

* * *

**Author's Note: "I hoped you enjoyed. ^^ I'll try to update as soon as possible. Touhou has become a recent fad of mine lately."**


	2. Growing Concern over Gensokyo

**Boundary of Flames**

(a Touhou Project & Shakugan no Shana crossover)

* * *

**Characters introduced so far:**

**Yukari Yakumo:** The Youkai of Boundaries and one of Gensokyo's oldest living youkai dating back to its founding and creation. She has a laid-back personality and mostly sleeps for the majority of time but she never turns a blind eye when it comes to a major incident in Gensokyo. Her main ability is the manipulation of boundaries which she can create gaps to travel and even battle with. Fans tend to portray her as a prankster and a troll because of her somewhat sinister tenacity.

**Ran Yakumo:** A nine-tailed kitsune (fox) youkai and Yukari's shikigami. She was originally a fox but turned into a youkai once she had grown all nine tails. Not much is known about her past or how she became Yukari's shikigami in the first place but she is very loyal to Yukari and ironically has a shikigami of her own. It is believed she possesses great abilities beyond what a standard youkai could do.

**Chen:** A two-tailed nekomata (youkai cat) and Ran's shikigami. Her strength and abilities vary depending on how close she is to Ran but unfortunately can turn rebellious when she is too far away.

* * *

**Chapter 1: Growing Concern over Gensokyo**

-Gensokyo-

It was still a normal day in Gensokyo. Despite the sudden appearance of the crack in the border, most of the humans and youkai barely even notice it in the sky and went on with their daily lives as usual. The human village was still bustling and many fairies and youkai continued roaming the land without incident. The inhabitants of Scarlet Devil Mansion, the underground city of former Hell, and Senkai don't even notice the crack to begin with due to their isolation. The flames still continued to seep through the border and so far, only the spirits of the Netherworld were showing concern. The crack continued to expand slowly and as it did, the flames continue to spread across. Ran was back at Yukari's house with Chen and observed the spreading damage caused by these mysterious flames. Ran feared that these flames could do more than just destroy the border, she sensed that these flames would eventually consume all of existence of Gensokyo until there is nothing left of the mythical land. Both humans and youkai; even the living and the dead would be erased from existence forever if these flames were allowed to spread across. Chen also observed the flames and was getting just as concerned as Ran.

"What's going to happen to the border Ran-sama?" Chen asked. "Are we going to have to leave and live in the Phantasm Realm with Yukari-sama?" Ran looked at Chen and smiled to cheer her up.

"There's no need to worry Chen. I'm sure that we can come up with a solution to put an end to the growing threat." Ran said. She went into deep thought and remembered what Yukari said to her just before she returned to Gensokyo. "Chen, come with me. It's time to gather the team." Ran said. "Hai Ran-sama!"

* * *

-Scarlet Devil Mansion-

Within the courtyard of the mansion, Hong Meiling is doing her usual business of maintaining the garden and guarding the gate. Meiling is calmly watering the plants until she stopped and carefully listened. She noticed someone is approaching the gate and went into defensive stance, then ran towards the gate. "Who's there?!" Meiling screamed. "I won't let you harm the mistres…" She was cut short when she noticed Ran and Chen approaching the mansion and recognized who they are. "Hey! You're the two shikigami of the Boundary Youkai."

"Konnichiwa Meiling! May we have access into the mansion? We need to have an important discussion with your mistress."

"Uhh… Sure. Right this way." Meiling directed the shikigami to the mansion.

As Ran and Chen walked into the courtyard, Meiling stepped onto a hidden glyph on the ground and then exploded in a burst of magical energy. Meiling was charred all over her body. "Oh my. I guess the fairies are at it again with their pranks." Ran said. Soon, Meiling heard laughter behind the wall and turned around to see the Three Mischievous Fairies make a hasty retreat. Meiling got furious. "I'm gonna get these three one day! The next time I see them, I'm going to drag them to the mistress for a severe punishment!" Despite the prank, Ran and Chen continued into the mansion's foyer where they are greeted by Sakuya.

"Welcome! What brings you two shikigami here?" Sakuya asked.

"We would like to see your mistress. Can you take us to her please?" Ran answered.

"I guess that can be arranged. I'll see if the mistress has some free time. Follow me." Sakuya said.

As the three walked around the mansion, Chen looked at the unfamiliar architecture style with curiosity. "This place is strange." Chen commented. The three eventually arrived at Remilia's room and Sakuya knocked on the door. "Mistress, we have visitors from the Yakumo household."

"Let them in." was Remilia's succinct answer. Sakuya then opened the door to let the shikigami in and greet the young vampire mistress who was standing with a somewhat cheerful disposition in her face.

"You must be the two lackeys of that meddlesome Boundary Youkai. What business do you have with the Scarlet Devil such as myself?" Remilia said with a smirk.

"To properly correct you Mistress Scarlet, we are shikigami, not lackeys. Also, we have a very important discussion about the current situation concerning the border." Ran said.

* * *

-Netherworld-

Within the Saigyouji household, Youmu continues to watch the ever-expanding crack within the border. The range of the seeping flames has increased since when the crack first appeared and now the spirits of the Netherworld are growing more restless. To Youmu's concern, it won't be long until the flames would reach the Netherworld and consume every last spiritual essence to nothing. Yuyuko watches the growing threat alongside Youmu.

"Oh my! I wonder what will become of our beloved home and the beautiful cherry blossoms that bloom within our trees?" Yuyuko said in concern.

Youmu looked at her mistress with a look of determination in her eyes. "Not to worry Yuyuko-sama. I will protect the Netherworld, no matter what threat stands in the way. I will not let these flames consume our home." She said.

Just then, Yuyuko sees two familiar faces approaching the household. Ran and Chen walk to the front entrance to greet the ghost mistress and her half-ghost servant. "Long time no see fellow shikigami of a friend. I guess this may be the wrong time for visitors however." Yuyuko said.

"I know. The situation of the border is much worse here than it is on the ground. That's why I came here for a discussion?" Ran said.

* * *

-Eientei-

Deep within the Bamboo Forest of the Lost where few tread is a mysterious Japanese-style mansion inhabited by rabbit youkai. Within the mansion, the two exiled inhabitants of the moon; Eirin Yagokoro and Kaguya Houraisan are preparing for the Moon Festival just one week away with the help of Reisen Udongein Inaba and Tewi Inaba. Eirin is making sure that everything is running smoothly as planned.

"Be careful with those diagnostic vials! They are key items for discovering new vaccines and medicines!" Eirin warned the rabbits as they were moving the stuff around. Kaguya is just sitting on the floor watching the preparations move underway and curiously looks at a vial containing a strange purple liquid.

"Say Eirin, what is this type of medicine you came up with?" Kaguya asked.

"That is a special medicine designed for visitors wanting to go to Scarlet Devil Mansion. It can heal vampire wounds and restore blood loss within minutes should the Scarlet Devil have blood cravings. I'm not sure if it works in a "Flandre" situation though." Eirin explained.

"I see. Although in my case, I do not have to worry because with the hourai elixir making me immortal, even those two vampires don't scare me." Kaguya smiled at the thought.

Just then, Reisen entered the room. "I'm sorry to interrupt but the skikigami of the Border Youkai arrived just now. They request a discussion." She said.

"Let them in!" Eirin ordered. With a bow, Reisen brought Ran and Chen into the room. "What business do you have with us? Did you come for the preparation of the Moon Festival?" Eirin asked.

"The full moon is one week away correct?" Ran said.

"Hai!" Both Eirin and Kaguya answered.

"Unfortunately, there may not even be a full moon if the situation of the border gets worse." Ran said.

"What do you main?" Kaguya asked. Ran then directed Eirin and Kaguya outside and pointed to the crack with seething flames in the sky. Both look at it with shock. "How did this happen?" Eirin said.

"Yukari-sama is looking into it now. In the meantime, it is important to have this discussion." Ran explained.

* * *

-Moriya Shrine-

At the summit of the Youkai Mountain lies a shrine run by Sanae Kochiya. The kappa Nitori Kawashiro is conversing with the shrine's goddess Kanako Yasaka along with the resident from former Hell Koishi Komeiji.

"The Mountain Industrial Revolution Project has been a huge success for us kappas that we were able to invent new technology we were unable to before. That's why I would like to increase the nuclear output a bit because I have some new experiments to test out." Nitori said.

"I see. I'm ok with this as long as the Komeiji Sisters agree." Kanako said.

"Just wait for a moment please. I'll see if big sis Satori will approve of your request." Koishi said with a smile, then she flew back down the mountain.

At the shrine entrance, Sanae could see Ran and Chen flying towards the mountain. As they land, they are greeted by the shrine maiden. "Konnichiwa!" Sanae bowed. "Have you come here to offer your prayers of faith to our goddesses?"

"Not today unfortunately. I came here to discuss a situation to your goddesses instead." Ran said.

"I see. Follow me. I'll see if Kanako-sama has some time." Sanae said.

As Ran and Chen follow Sanae to the shrine, Chen sees Suwako who is beside Kanako watching her conversation. "One of the shrine's goddesses is a frog? I wonder if she's playful?" Chen said in curiosity.

"Be careful Chen. Suwako is one of the strongest beings in Gensokyo and she doesn't take others lightly." Ran warned Chen.

"Kanako-sama, we have visitors." Sanae bowed. The two shikigami approach the goddesses and the kappa.

"What brings you here to the shrine? I'm in a middle of a conversation to increase the Mountain Industrial Project to the next level." Kanako said.

"Maybe they were sent here by the Border Youkai to cause trouble." Suwako speculated.

"Don't jump to conclusions Suwako. We just need a straight answer, not an unnecessary danmaku match." Kanako said.

"We are here because there is a situation with the border. We need to discuss the situation." Ran explained as she pointed to the sky where the crack in the border is.

* * *

-Palace of Earth Spirits-

Deep within the underground of what used to be Hell is an underground city inhabited by Oni. In the center of the city is a dark but spacious palace; built for the purpose of containing the evil spirits that emanate from the Hell of Blazing Fires. Inside the palace, Koishi is in a conversation with her older sister Satori Komeiji and her pet kasha; Rin Kaenbyou (or Orin for short).

"So you request Utsuho to increase the nuclear output for Kanako and the kappas?" Satori said.

"Hai! The kappa Nitori requests it for increasing the Mountain Industrial Project to the next level, and also to perform new experiments. I was wondering if you would approve of the request." Koishi said.

"I'm still not fawned with the idea of Kanako giving Utsuho nuclear fusion powers without my permission. However, seeing that the damage cannot be undone, I will approve of their request just this once." Satori said.

"Besides, Okuu has learned to use these powers wisely now since everything is cleared up." Orin said with a smile.

"Don't forget that you were responsible for releasing the spirits and the sealed Palanquin Ship above ground." Satori reminded Orin.

"Gomen nasai! It was the only way to get their attention. What else could I have done?" Orin said.

Soon, Yuugi Hoshiguma enters the palace with Ran and Chen in tow. "What's up mind reader? You have some visitors from above ground." She said. The two shikigami approach Orin and the Komeiji Sisters. Both Chen and Orin looked at each other.

"Oh hey, a fellow kasha. I guess I do need an extra hand with the corpses around here." Orin said with a smile. However Chen shook her head. "I…I'm not a kasha, I'm a nekomata. I don't intrude in funerals to steal corpses." Chen corrected Orin.

Satori approached the two skikigami. "So you two came down here to warn us about the growing threat in the border." She said.

Chen was surprised. "Whoa! How did you know that? We didn't even tell you and your underground."

"My third eye can see into the hearts of living things, revealing their innermost thoughts. It would seem that the threat will eventually consume Gensokyo if something is not done." Satori explained.

"I guess you already know that much with your mind reading powers, so I'll just cut to the chase then." Ran said.

* * *

-Myouren Temple-

Within the temple, Byakuren Hijiri and her disciple Shou Toramaru look at the crack in the sky. Nazrin has already told them about it and the rest of the temple inhabitants grow worried of what might become of the border. "This is most unfortunate." Shou spoke. "We may never get the humans and youkai to co-exist if the border is destroyed. It will only create more tension between each other once they are exposed to the rest of the outside world."

"My only dream is to fulfill my brother's wish. Such a dream will not happen the way things are now. Something must be done." Byakuren stated.

"So how should we take action Byakuren-sama? Should we gather the humans and youkai to work together in this situation?" Shou suggested.

"That alone in itself will not work." A voice came from above. Byakuren and Shou looked up to see Ran and Chen descend down in front of the temple. "There is more that needs to be done than just gather everyone. The threat lies in the outside world after all." Ran said.

"I see. So all we need is a proper plan." Shou said. "I guess someone with years of experience like you should know what to do in this situation."

"Yukari-sama is already looking into it know. In the meantime, I will discuss the plan until she returns." Ran explained. Soon after, Nazrin stepped out of the temple only to stop at the sight of Chen. "AAAAHH! A CAT!" Nazrin screamed then ran back inside. Chen was about to give chase but Ran stopped her just in time.

* * *

-Hakurei Shrine-

The Hakurei Shrine is Gensokyo's most important feature. Located at the very edge of the border, the shrine is tasked to maintain it along with the shrine's owner; the Shrine Maiden of Paradise: Reimu Hakurei. It was just another ordinary day for Reimu and her shrine-maintaining Oni Suika Ibuki. Due to Reimu's laid-back personality, she failed to notice the crack in the border with spreading flames. She is just sitting at the front step sipping tea as she watches Suika do some maintenance on the shrine to prevent another "Tenshi" scenario. Soon, something catches her eyes' attention and two familiar faces approach the shrine. It was the two shikigami Ran and Chen. Reimu got up and stopped sipping her tea. "Suika! You can stop now. Someone's coming here." Reimu ordered. Suika stopped and looked at the approaching shikigami. "Well what do you know? It's Yukari's lackeys!" She said in a cheerful tone.

Reimu confronts the shikigami. "Ok, what is it? Does Yukari need another favor?" Reimu asked bluntly.

"Far from it." Ran shook her head. "I came here to organize a plan with the current situation."

"What situation? What are you talking about?" Reimu said confused.

"You mean you do not know what is happening with the border. I expected more from you to handle this situation professionally. No wonder the rest of Gensokyo sees you poorly." Ran stated.

"Slacker!" Chen said critically to back up Ran's statement.

"Look, I honestly have no idea what you are talking about. I was busy renovating my shrine." Reimu explained.

"…and look who's doing all the work." Suika said.

With a sigh, Ran pointed to the sky where the crack in the border is. Reimu was shocked to see such a crack exist and the flames that spread from it. "But, how is that possible?" Reimu said in disbelief.

"The threat of the border lies in the outside world. Yukari-sama is already investigating the main cause outside so I gathered the inhabitants around Gensokyo who would deal best for the situation. We'll have a meeting here at the shrine when Yukari-sama returns." Ran explained.

"I see. I didn't think it would be this bad. I'll go tell Marisa-san and Alice about this because they live isolated in the Forest of Magic, and Marisa-san can be a bit out-of-it these days." Reimu said, still remembering Marisa attacking her for no reason during the Fake Moon Incident.

"That would likely be best for us. Both Marisa and Alice possess great abilities as skilled magicians in Gensokyo." Ran agreed.

Just as they are talking, Chen felt the footstone underneath her beginning to push up. "Whoa! What the…" Chen said. She jumped out of the way and everyone looked at the footstone to see the True Administrator Toyosatomimi no Miko push it up and popped out of the hole.

"Miko! What are you doing here?" Reimu said surprised.

"Well, I heard things have gotten pretty bad with the border of Gensokyo. This could threaten Senkai so one of my Hermits went out to check and told me that a certain shikigami is gathering the residents throughout to deal with the situation. I thought maybe I should join the gathering." Miko explained.

"You came just in time Miko. All of Gensokyo is threatened so it would be prudent to include Senkai along with the gathering." Ran said.

"So it's settled then." Miko said with a smile. "When is the gathering taking place?"

"We will all gather at the Hakurei Shrine. We just need to wait until Yukari-sama returns from her investigation." Ran said.

"CRACK!"

The sudden noise caught the attention of the group. They looked up to see the crack expanding and as it did, the flames continue to spread with even further distance. "I fear that we may not have much time left. Please return quickly Yukari-sama." Ran prayed.

* * *

-Unknown Location-

Far from the boundaries of Gensokyo hidden deep within the mountains, there lies a large, modern city running along a river which leads into the Pacific Ocean. Being a branch of Tokyo, the city contained many towering skyscrapers, branching streets, and buildings of Japanese and Western variety. The river it ran along contained many suspension bridges that connect the two sides of city. Yukari stands on one of the supports of the bridges and takes a good look around the city.

"So this is Misaki City." Yukari said to herself. "I better track down that youkai quickly and get information before the abnormality in the Hakurei Border grows." Yukari then hovered from the bridge and flew around the city to have a better view. Being in the outside world many times before, Yukari was familiar with how humans lived and how their lives are tied to technology. Misaki City was no different, however Yukari had a strange feeling about the city.

"How very strange, I feel as if this city never existed before." She said. As she continued to fly around the city, she also sensed a hidden supernatural presence. Yukari eventually flew down closer to the streets but not too close where she can be seen. Watching the humans below, it was usual business but then something down the street caught Yukari's attention. She spotted a human disappearing into flames; the same colored flames that were seeping through border. What also caught Yukari by surprise is that the other humans didn't seem to notice what happened to that human, as if he never existed to begin with.

"How strange…" she thought. She continued flying around until something caught her off-guard. Within an instant, the city was covered by the dark-red haze. Everything down the streets came to a halt. The humans were colorless and completely frozen in time, something that Yukari thought Sakuya could do much easily if she were outside Gensokyo. To Yukari, this was a surprise because she had never encountered something like this in the outside world before.

Shoving the thought aside, Yukari went back to searching regardless of what was happening around her. "The youkai is definitely nearby if this red haze appeared." She said. With the humans frozen, Yukari was able to search the streets without having to worry of being seen. As she wandered through the streets, she runs into and confronts an ugly white creature standing before her.

"Oh my, now what type of creature is this?" Yukari thought. She saw the creature consume a frozen human nearby and too her surprise, the human completely disappeared into flames and no trace of him left. The creature then turned its attention toward Yukari. "Power of Existence!" it screamed in a voice that can only be described in a horror movie.

"Looks like I overstayed my welcome." Yukari said, and then disappeared into a gap before the creature reached her. The creature looked around confused while Yukari reappeared on top of a nearby building for a much safer view. As she continued to watch the creature's rampage, a large stream of crimson flames struck the creature from behind and cut it in half before disappearing into flames itself. Yukari turned to see the blazing-haired girl who was with a young boy holding a giant broadsword.

"I guess that's the last of them Shana." The boy said to the girl. "Do you sense anymore rinne?"

"I sense no more distinct Power of Existence within the city. I believe we have killed all of them Yuji." The girl Shana answered. "You have done well on your part."

"Arigato! I guess I have been improving on my training lately." The boy Yuji said. Shana smiled a blushed a bit. "Keep training Yuji. You will soon master the techniques of Flame Haze."

"_Now we must fix the damage. Shana! Yuji! You know what to do._" Said the mysterious voice that came from nowhere.

"Hai Alastor!" Both of them nodded. Yukari observed as both Shana and Yuji restore their surroundings using a strange supernatural power she never saw before. "Fuzetsu Release!" Shana shouted as she released the red haze around the city. Everything went back to normal.

"Let's head back home. I'm a bit exhausted from having to battle this much rinne before." Yuji said. Shana nodded with a smile and the two walk down the street. Yukari watched the two from the building above.

"I have finally found you mysterious youkai." Yukari smirked before disappearing into a gap once more.

**End of Chapter**

* * *

**Author's Note: "First Chapter done. I have decided to include the Ten Desires cast as well because I feel they are being left out for the fact the game was too easy. I hope you enjoyed! ^^"**


	3. The Border Youkai and the Flame Haze

**Boundary of Flames**

(a Touhou Project & Shakugan no Shana crossover)

**Chapter 2: Finding the Truth – The Border Youkai and the Flame Haze**

Yukari Yakumo has been investigating the outside world to find the cause of the weakening border. Her search has led her to Misaki City where she has followed a young girl with blazing-red hair whom Yukari believes is the true cause of the problem. The outside world however is completely different from the one Yukari had known where it was thought magic and supernatural phenomenon no longer existed. How will Yukari cope with the reoccurring red haze that stops time and beings that consume human existence? Yukari presses onward, following the blazing-haired girl Shana and the young boy Yuji in hopes of preventing Gensokyo's collapse.

* * *

-Misaki City-

Misaki City; to some, it is just another ordinary city in the world but to Sakai Yuji, it is more than that. Misaki City is home to many strange and dangerous phenomenon that has plagued the city as long as he could remember. The humans in this city live miss fully unaware of the surrounding danger from Guze: the Crimson Realm. Supernatural beings from the Crimson Realm called Guze no Tomogara cross over to the human world and feed on humans for their Power of Existence. The extensive actions caused by the tomogara have caused a gradual distortion of existence that is rapidly growing as they progress. Fearing the worst, Crimson Lords and Crimson Gods have contracted with humans to become Flame Haze. The Flame Haze hunt down the tomogara and prevent more mass distortions that could lead to destruction, an every-growing conflict that has lasted for thousands of years.

However, whatever damage that was done cannot be fully restored, as Yuji had learned the hard way on the faithful day he met Shana. Humans who already have their Power of Existence consumed no longer exist as full human beings. Instead, they exist as torches; temporary replacements for the already-consumed humans in order to delay the distortions caused but these torches don't last forever. They will eventually burn out of existence along with the memories of the human it replaced. Yuji himself had his existence already consumed so he is a torch but because of the Reiji Maigo inside of him, his torch continues burning so he is a Mystes. Still, it doesn't replace the fact that he was once human so the life he had lived then is completely gone. His fate now tied to the conflict between Flame Haze and tomogara. Yuji continued to walk home with Shana from his recent battle. Unknown to both Shana and Yuji is that the Border Youkai Yukari is secretly following them from within the Phantasm Realm.

"Itte… I think I may have overdone it a bit. I'm soar all over my body." Yuji complained as he walked.

"You're overdoing your training too much." Shana remarked with a smirk on her face. "A Flame Haze never wears him or herself in training or on the battlefield."

"But didn't Carmel-san call you off into the mountains to take care of some tomogara? I had to train myself harder than usual today because of your absence." Yuji said.

"_Yuji, be careful not to overdo your own training. Do not forget that as you train, you use up your own Power of Existence and the Reiji Maigo only restores it at midnight._" Said the voice coming from Shana's glimmering red pendant.

"I know. I was just taking some extra measures to make sure I was able to defend myself." Yuji explained.

"That's still no excuse for wearing yourself out. You should learn more." Shana remarked Yuji again.

"Ok, ok. I'm sorry." Yuji scratched his head.

As they were walking, they see a girl with short light-brown hair walking towards them. Both Shana and Yuji recognized her as Yoshida Kazumi; a very close classmate and friend. Yuji was happy to see Kazumi but Shana had an intense glare in her eyes, inclining that she was not so happy.

"Yoshida-san, Konnichiwa!" Yuji bowed.

"Konnichiwa Sakai-kun and Shana-san." Kazumi bowed back. "So how was your day?"

"It went pretty well, but what about you? You were not hurt from that recent rinne attack were you?" Yuji asked.

"Ie!" Kazumi answered as she blushed. "I was near my house when it happened so I took cover. Thank you for your concern."

"I was just wondering because both Shana and Carmel-san had to hunt down tomogara in the mountains. I'm glad you're safe." Yuji smiled. Kazumi blushed as she smiled back.

Shana started to show a hint of jealousy as she watched both Yuji and Kazumi talk. She knew very well that she was in a love triangle with Kazumi to win Yuji's heart so she feared Kazumi may pull a trump card that will make Yuji choose Kazumi over her. Without thinking, Shana continued walking past Kazumi.

"uhh… What's wrong Shana?" Yuji asked.

"It's nothing! Let's go Yuji!" Shana answered bluntly.

"But don't you want to talk to Yoshida-san…"

"URUSAI! URUSAI! URUSAI! I said let's go!" Shana shouted as she shook her head.

Yuji was silent, wondering why Shana is always uneasy around Kazumi. "I know these two are in a love triangle but would it hurt Shana to say hello?" He thought.

"Gomen nasai Yoshida-san, I'm sure Shana doesn't mean her attitude." Yuji said.

"I know, I'm used to it now." Kazumi smiled at Yuji. "Shana-san may be stubborn but she is a nice person on the inside."

"So I guess this means I will be making a decision soon huh?" Yuji wondered.

"Yuji!" Shana shouted.

"Hai!" Yuji nodded. "I have to go now Yoshida-san. I'll see you again soon." Yuji then ran to catch up with Shana who briefly glared at Kazumi before turning away.

"I won't lose to Kazumi!" Shana thought, determined to not lose the bout she made with Kazumi several months ago.

Kazumi watched the two walk down the street. She knew that it was almost time for Yuji to make a decision of who he will choose to be with. "I have to work hard this time." Kazumi thought to herself as she continued walking to her house. However as she was about to turn in an empty corner, a gap appeared underneath her feet and Kazumi fell in with a scream. "AAAAAHH!" The gap then quickly disappeared without a trace.

Kazumi was scared. Still trying to piece together what had happened in her mind, she found herself drifting through an eerie purple realm* that was filled with hundreds of eyes staring at her.

"Where am I? What's going on?" She said in fear. Although she was used to the Fuzetsu, She had never seen a realm like this before and wondered if a tomogara was responsible.

Within the darkness, Kazumi could see a silhouette figure walking towards her. As the figure got closer, Kazumi could see the figure appears to be a young woman with blond hair, wearing a purple dress, a pink mob cap, and holding a parasol decorated with red ribbons. Her purple eyes match the eerie color of the realm itself as well as the surrounding eyes and as Kazumi looked at them, she knew those eyes bear wisdom in them. "W… Who are you?..." Kazumi asked.

"Allow me to introduce myself." The woman stopped. "My name is Yukari Yakumo; the Youkai of Boundaries and I have dragged you hear in Phantasm because you seem to have a close relation with that blazing-haired girl."

Kazumi's eyes widen in shock. "You mean Shana-san? So you must be after the Reiji Maigo inside Sakai-kun."

"The Reiji Maigo? I'm afraid I don't have the slightest idea of what you are talking about but if you mean that boy she was with, the answer is no. I'm here because of that girl herself." Yukari said.

"But why Shana-san?"

"You see, the girl you call Shana is widely responsible for the weakening of the Hakurei Border. So to sum things up, I'm going to make her "deceased"* a bit." Yukari smirked. Kazumi gasped at the thought.

"I'm afraid I'm running out of time to chat with you so I will send you to Gensokyo for a later reference of the border situation. I must get back to my investigation." Yukari said.

"Gensokyo? Wait…" Before Kazumi could finish, a gap appeared and started pulling Kazumi inside it. "EEEK!" Kazumi shrieked. Yukari only stood there with a smile as she watched Kazumi get pulled in one of her gaps.

"Just a little warning, when you arrive in Gensokyo, do not trust everyone you see. Otherwise, you'll end up as a youkai delicacy." Yukari said to Kazumi before her head disappeared with one last scream. "SAKAI-KUN! SHANA-SAN!" Yukari looked at the spot where Kazumi once stood.

"Take good care of this girl Ran. We need her for the situation we are in." Yukari said to herself. After that, Yukari continued walking into the depths of Phantasm.

* * *

-Gensokyo-

Within an isolated forest where most of the sunlight was blocked by the surrounding trees, a gap appeared and Kazumi fell out of the gap and onto the ground. "Itte…" Kazumi said as she staggered to get up. Once she had brushed herself off, she looked around the forest.

"Where am I?" She said in confusion and even wondered if she was near Misaki City anymore. Her silence was cut short when she heard a rustling sound coming from behind. "W… Who's there?" She said in fear, expecting to see something she wouldn't expect. The rustling got louder and Kazumi saw a girl dressed in mostly black-and-white, had her arms sticking out in a cross position as if she were crucified, and was covered in a sphere of darkness.

"Oh hey, a human being. Finally!" The mysterious girl said as she confronted Kazumi.

Kazumi backed off a bit. "A… Are you a tomogara?" Kazumi asked.

"My name is Rumia; the Youkai of Darkness. Why would a human like you bother asking youkai without any clue of what's going to happen to you?" The girl said.

"I…It's just that I wanted to make sure you're not a tomogara. And why are you sticking your arms out like that?" Kazumi asked in curiosity.

"It's because that witch said I adopted the decimal system*. But enough about that, It's time to eat!" Rumia said as a smirk appeared on her face.

"Nani!?" Kazumi said confused. Before she knew what was happening, the sphere of darkness around Rumia expanded and covered the entire forest. Rumia's face transformed into a demonic look.

***Apparitions Stalk the Night***

"EEEEK!" Kazumi shrieked in fear at the sight of the transformation and began to run as fast as her legs could carry her. "You're not getting away!" Rumia shouted in a demonic voice, and then started flying after Kazumi and shooting relentless danmaku at her.

"AAAAAAHH! Sakai-kun! Shana-san! Where are you?!" Kazumi screamed as she tried to outrun Rumia and her danmaku. Running was starting to become useless however as Rumia was gaining on Kazumi at high speed and closing in fast.

"Itadakimasu!" Rumia shouted as she closed in at Kazumi and opened her mouth for a bite. Kazumi looked backed and closed her eyes. "AAAAAAAHH!"

Suddenly, several kunai bullets struck Rumia before she could catch Kazumi. "Raaargh!" Rumia shrieked in pain. Kazumi opened her eyes and turned to see a woman dressed in a blue-and-white outfit and had nine fox tails. The woman glared at Rumia as the Darkness Youkai backed off at the sight of the fox tails.

"Aaaah! It's the shikigami of the Border Youkai!" Rumia screamed in fear before making a hasty retreat to avoid a confrontation. The veil of darkness lifted as she left the forest.

Kazumi looked at the nine-tailed woman standing before her and started to back off in fear. The woman slowly approached Kazumi.

"I knew I sensed a gap signature around this area. I assumed Yukari-sama sent you here?" The woman said. However, Kazumi remained silent, fearing that the woman may attack her.

"Please do not fear child. I will not harm you." The woman said. Kazumi broke her silence and spoke. "W… Who are you?"

"My name is Ran Yakumo. You appear to be a human sent from the outside world by Yukari-sama. Please, follow me. It's too dangerous around here."

Kazumi nodded. "Hai!"

* * *

-Misaki City ~Sakai Residence-

Shana and Yuji arrive at a small house down the street that was labeled with Yuji's family name. As the two enter the house, Above them, Yukari was secretly watching them from her gap. "I assume this must be that youkai's hiding place." She said to herself. "Now all I have to do is wait for an opportunity."

Inside the house, Yuji and Shana take off their shoes in the porch and enter the main room. Yuji looked around. "I guess Carmel-san isn't back yet." He said.

"Don't forget that Wilhelmina is a member of Outlaw. She will be absent for most of the time." Shana said.

"_I can still sense the presence of the Manipulator of Objects in this city. She hasn't gone very far._" The pendant said.

"Arigato Alastor. Then my guess is that she will be coming back soon. I'm going to take a bath." Shana said.

"Ok. I'm going to check on Okasan to see if everything is alright." Yuji said.

With that, Shana went upstairs and Yuji entered the main kitchen of the house. What he saw was the kitchen was a mess. There were food stains everywhere along with huge piles of pots and pans. Yuji wasn't surprised however, he knew this too well. "Carmel-san was definitely here recently." He thought. Yuji's mother Chigusa enters the kitchen.

"Oh, Yu-chan. You're home early." Chigusa smiled as she greeted her son.

"Oh hey Okasan. I'm guessing that Carmel-san was here recently." Yuji scratched his head.

"Hai!" Chigusa nodded. "Karumeru*-san said she was off to do some errands. This was her most recent work earlier this morning." Chigusa pointed out.

"I see. So I'm guessing she will be home soon then." Yuji said.

"Hai! By the way, how are things going with Shana-san? Have you finally made a decision?" Chigusa smiled.

"Umm… Not yet Okasan. I'm having a hard time deciding at the moment so I don't know how to tell Shana or Yoshida-san."

"Ah, I see. I'm sure your answer will come to you shortly Yu-chan. Just don't forget that if you do decide, try not hurt the feelings of the one you turned down on. You can still be friends either way." Chigusa smiled again.

"Arigato Okasan." Yuji smiled back. "I'll try to make a decision sooner."

Yuji then left the kitchen to let Chigusa clean up the huge mess made by Wilhelmina. He slowly went into deep thought about the decision he'll have to make soon. "Shana-san, I want to leave Misaki City with you one day. But Yoshida-san…"

Upstairs in the bathroom, Shana is calmly resting her body in the hot water of the tub. She too was deep in thought about Yuji's decision. "Yuji…"

"_You are still thinking about the ordeal between you Kazumi I assume?_" Alastor said, who was on a nearby shelf.

"Yes! It's just not fair. Kazumi is only human, and I'm a Flame Haze and Yuji is a Mystes. She doesn't fully understand that Yuji is no longer human and he even promised me to leave Misaki City with me." Shana said.

"_The fact that you are jealous is because you fear that if Yuji chooses Kazumi, she will be in danger of being a target to tomogara._"

Shana turned her head. "It is exactly what is like. Kazumi knows nothing about us."

"_So you also care for Kazumi's safety._"

"…Yes! Kazumi is only a human after all, and I want Yuji to keep his promise with me."

"_Unfortunately I have some bad news regarding Kazumi._"

"What is it Alastor?"

"_Earlier this afternoon, I felt Kazumi's Power of Existence vanish from this city entirely._"

Shana's eyes widen in shock. "What do you mean?! Did a tomogara consume her existence?!"

"_No, she still exists as a human but I felt an unknown presence in this city. Kazumi vanished the moment after you met her this afternoon._"

"Why didn't you tell me this earlier?!"

"_I didn't want Yuji to know about Kazumi's disappearance just yet. For now, I want to focus of finding out about this mysterious presence._" Alastor explained.

"I see. So is Kazumi still alive?"

"_I can assure you she is still alive. Her existence only vanished. She wasn't consumed by a tomogara._"

"Good. At least this way, Yuji won't panic." Shana said as she got out of the bath tub.

"_Be on your guard Shana. The unknown presence I feel is still within the city._"

"Yes!" Shana nodded.

* * *

Outside the house, the sun was already setting and it was starting to become night time. With the streets starting to become empty, Yukari emerged from her gap and floated over the house. A smirk appeared on her face.

***Charming Domination ~Who Done It?***

"So now is the perfect opportunity. Time for you to come out and play mysterious youkai!" Yukari said to herself. She lifted her parasol high in the air and was about to create another gap but before she could, the dark-red haze appeared and several white ribbons were coming in her direction. Yukari grazed the ribbons and countered the rest with her kunai bullets. "Oh, looks like we have a visitor." Yukari smiled.

Standing before Yukari was a woman with magenta hair and wearing a maid outfit. Her expression was almost emotionless as she glared at Yukari. "You will go no further! ~de arimasu" The woman said.

"Hmm? You don't appear to be human. So who and what are you?" Yukari asked.

"I am a Flame Haze; the Manipulator of Objects. I will stop you from obtaining the Reiji Maigo! ~de arimasu"

"_Engage!_" Said a mysterious voice.

Yukari only smiled as she confronted the Flame Haze before her. "You seem to take an interest in this "Reiji Maigo". I do not know what is going on but if you are going to get in my way, I'm afraid I will have no choice but to play danmaku with you on Lunatic Mode. Your chances of survival are minimal if you don't have proper grazing skills." Yukari said with a smirk.

Back inside the house, the red haze has caught the attention of Shana and Yuji.

"Yuji! The Fuzetsu!" Shana shouted. Yuji nodded and grabbed a giant sword that seems to be heavier than him but he could still lift it anyways. "I'm coming Shana!" He said. He soon joined with Shana and the two stormed out of the house.

"So where's the tomogara?" Yuji asked.

"_The Manipulator of Objects is nearby. I can feel her presence above us._" Alastor said.

The two looked up to see the Manipulator of Objects: Wilhelmina in a battle against the Border Youkai Yukari. The Flame Haze is trying to get close to Yukari for a fatal strike with her ribbons but the Border Youkai is keeping her at bay with her relentless amount of bullets. The Flame Haze was soon boxed in by the bullets and could not dodge them any longer, she was soon struck by them and was injured.

"Wilhelmina!" Shana screamed.

"Come on! We need to help her!" Yuji said. Shana nodded and the two flew up to aid Wilhelmina in battle. Shana went to check on Wilhelmina while Yuji confronted Yukari to defend them.

"Wilhelmina! Are you alright?!" Shana said.

The injured Flame Haze nodded. "Yes! I was just carless. This tomogara uses a combat method I haven't seen before. ~de arimasu."

"It's called Danmaku. I told you before, unless you have proper grazing skills, your chances of survival are minimal. You are better off on Easy Mode." Yukari said.

"So what is your purpose?! Are you here because of the Reiji Maigo inside me?!" Yuji said.

"It's funny how you ask that question. Earlier today, the girl you spoke with asked that same question. The Reiji Maigo or whatever that is seems to be a popular thing with you." Yukari answered.

"That girl, do you mean Kazumi?!" Shana said with anger burning in her blazing-red eyes.

"What have you done to Yoshida-san?!" Yuji demanded.

"I sent your friend to Gensokyo. Do not worry, she is still alive. I need her however for a situation that threatens our world." Yukari explained.

"_Gensokyo?_" Alastor questioned.

"Now if you'll excuse me, I have a "date" with this blazing-haired girl so if you want to avoid Phantasm Mode danmaku, I suggest you run away boy!" Yukari glared at Yuji.

"Not a chance! I will not let you harm Shana!" Yuji said as silver-colored flames appeared in the palm of his hand.

Shana drew out her sword blazing with crimson flames. "I will never forgive you for what you did to Kazumi! Now perish!"

"Now this should be fun." Yukari smirked. "I haven't had this much fun since my battle with the shrine maiden."

**End of Chapter**

* * *

**Author's Note: "I hope you enjoyed. Next chapter, the Flame Haze and the Mystes battle the Phantasm Stage Boss. Until next time… ^^"**

* * *

***Notes***

*It is actually unknown what the true color of Yukari's gaps are. ZUN's earlier drawings show the gaps to be crimson red while later drawings and fan art show the gaps to be either dark-purple or black. I decided to go with purple because it matches Yukari's personality very well.

*A reference to Scarlet Weather Rhapsody. In Yukari's story, Yukari said she was going to punish the Celestial Tenshi by making her "deceased". That however is just a figure of speech and that Yukari was only going to beat some sense into Tenshi.

*A reference to Embodiment of Scarlet Devil. In Marisa's scenario, Marisa commented on Rumia's pose saying how she looked like the kanji for the number 10. Hence where Marisa thought Rumia adopted the decimal system.

*Yuji's Mother Chigusa speaks in a form of Japanese where foreign names are pronounced in their katakana counterparts. Wilhelmina's last name "Carmel" is pronounced "Karumeru" in Japanese.


End file.
